Wire coating



March 1, 1966 M. J. STOBIERSKI WIRE COATING Filed Sept. 14, 1962 INVENTOR.

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United States Patent O 3,238,059 WIRE COATING Michael J. Stobierski, 127 Rocky Rest Road, Shelton, Conn. Filed Sept. 14, 1962, Ser. No. 223,735 1 Claim. (Cl. 117ll(l2) This invention relates to method and apparatus for coating wire. More particularly, the invention relates to method and apparatus for applying a thin copper coating to a ferrous wire.

It is common in the wire industry to manufacture metallic wire having a thin coating of another metal. One example is copper-coated steel wire which is widely used for various purposes. One of its advantages is its resistance to rust as the copper provides a rust-proof coating.

One widely used method of applying a thin copper coating to wire is to employ a solution of copper sulfate or other copper salt. Copper will plate onto mild or ordinary carbon steel by simply immersing the steel in an aqueous solution of a copper salt. In accordance with the prior art, large coils of wire, each of which may weigh as much as six hundred pounds, are placed by a crane into a large tank containing copper sulfate solution. Each coil is left in the solution for several hours until copper has deposited to a sufiicient thickness on the wire surface. After the wire has been coated, the coil is lifted from the tank and is placed in a water tank to rinse off the plating solution. It may then be lifted from the first rinse tank and immersed into a second rinse tank to complete the removal of residual solution. Similar techniques are followed for depositing other metals on various kinds of wire.

A number of factors prevent the prior art procedures from establishing satisfactory coatings on wire. Because the wire is in a coil, it will be seen that various coils may contact one another. Therefore, the solution is not allowed to circulate freely about any one coil and portions of each coil may not be coated. Furthermore, the fact that the wire is coiled also prevents adequate contact with the solution of each and every linear portion of wire contained within a single coil. Furthermore, the procedure described above may be considered a batch process, rather than a continuous process. Therefore, it is inherently less efficient and involves the use of considerable labor, such as required for lifting coils from one place to another throughout the operation. Another disadvantage of the prior art method of copper coating ferrous wire is that as the copper from the solution plates onto the wire, the iron content of the solution tends to increase due to iron from the wire going into solution. Eventually the iron content reaches such a level that the solution becomes unusable. At this point the solution is discarded and a new batch is made. This also contributes to the inefiiciency and waste of labor employed in the prior art methods.

Accordingly, it is the primary object of this invention to provide improved method and apparatus for coating metallic Wire. Other objects are to provide such an invention wherein the applied coating is highly uniform; wherein the coating process is carried out on a continuous basis; and wherein such process is conducted with maximum efiiciency and with minimum waste of labor and material.

The manner in which the above objects are attained will be more apparent from the following description, the appended claim, and the single figure of the attached sheet of drawing, which illustrate in a perspective view, partially cut away, one embodiment of apparatus suitable for practicing this invention.

The above objects are attained by continuously passing a length of wire through a suitable metallic salt solution for a length of time sufi'icient to achieve the desired coating. The wire is then passed through a rinse tank and from thence to a final collection point. Simultaneously with the passage of wire through the salt solution, new salt solution is continuously being mixed in the proper proportions and fed to the solution tank.

The single figure of the drawing illustrates mixing apparatus M in combination with treating apparatus T. The mixing and treating apparatus are illustrated partially cut away to more readily indicate their construction.

The mixing apparatus is employed to prepare the plating solution required in the treating apparatus. To this end there is provided a suitable tank 10 having an outlet 12 leading to a pump 14. A suitable container 16 is arranged to feed acid into tank 10 through an adjustable opening, such as a valve 18 and feed line 15. For purposes of illustration, it will be assumed that the method and apparatus being described are for use in plating copper onto ferrous wire. Accordingly, an aqueous solution of copper sulfate is employed. Consequently, in the mixing apparatus M, water, copper, and sulfuric acid are mixed to form a solution of the proper strength. The acid in container 16, therefore, is sulfuric acid. Water is supplied from line 17, controlled by valve 19. A bin 24 having a feed spout 22 is positioned so as to feed its contents by gravity into mixing tank 10. Bin 20 contains copper dust or a suitable equivalent, such as the products manufactured commercially and sold under the trademarks Copperdene and Redskin. In order to control the rate of flow of the copper from bin 20 there is provided an adjustable feed slot 24 which is set at the desired opening by means of an externally extending handle 26. In order to maintain gravity flow of the cornminuted materials from bin 20, there may also be provided a suitable agitator 28 operated by a motor 30. To keep the solution properly stirred, thereby enhancing solution formation and also maintaining it at a uniform strength throughout the tank, there is provided a mixing motor 32 for driving a mixing propeller 34 via a drive shaft 36. In addition, a thermostat 38 may be positioned on the tank to maintain the temperature of the solution by means of suitable heating coils or other heating apparatus (not shown). Pump 14 extracts the mixed solution and passes it through supply conduit 40 to a suitable liquid injection apparatus 42 positioned in one end of the plating tank 44.

The illustrated treating apparatus T comprises an elongated trough-like container which is divided by a transverse wall 46 into a plating tank 44 and a rinsing tank 48. Injection apparatus 42 is not illustrated in more detail because its construction is not critical to this invention. Apparatus 42, for example, may be comprised of several spray heads of commercial design which are resistant to the solution being sprayed. An overflow drain pipe 50 is threaded into a drain 51 in the floor of plating tank 44 at the end opposite the spraying apparatus. Drain 51 is connected to a recycling conduit 52 having a shut-off valve 58. A recycling pump 54 pumps the solution through conduit 52 back into tank 10. Overflow drain pipe 50 may be unscrewed from drain 51 to allow the entire contents of tank 44 to be drained. The solution inlet end of tank 44 may be provided with a cover 61) for preventing splashing and containing the sprayed solution within the tank.

At each end of tank 44 there is provided a plurality of idler sheaves, each grooved for retaining a wire on its periphery. The sheaves at the inlet end of tank 44 are indicated generally by the numeral 62. The sheaves at the outlet end of plating tank 44 are indicated generally by the numeral 64. Each set of sheaves 62 and sheaves 64 may be positioned on a common axle extending transversely along the Width of plating tank 44. Treating ap- 3 paratus T may also be provided with suitable brackets 66, 68 positioned above the apparatus substantially over transverse wall 46. Brackets 66, 68 support an axle 70 upon which is positioned a rotatable idler sheave 72. A guide she-ave 74 is located near the bottom and within the rinsing tank 48. A final idler sheave 76 is located above the rinsing tank to support the wire emerging therefrom.

In coating wire in accordance with the method and apparatus of this invention, a solution of proper strength is first mixed in tank 10. One such solution, which has been found to be satisfactory for copper coating, is mixed in the ratio of twenty-five gallons of water, four pounds of Copperdene and one gallon of sulfuric acid. Tank is approximately half filled with such a solution and it is injected into plating tank 44 by means of injection apparatus 42 to a depth sufficient to cover the sheaves. The wire 78 to be coated is passed into the plating tank from a suitable pay-off reel (not shown). Wire 78 is passed under sheave 621 and through the plating solution to sheave 641. The wire is then threaded to successive sheaves as shown, namely, to 622, 642, 623, 64.3, 624, 644, 625 and 645. From sheave 645, wire 78 is guided up out of the plating solution and over sheave 72. It will be noted that the wire is kept separated as it passes through the solution so that its entire surface is uniformly coated. It then enters rinsing tank 48 which contains plain water and is guided through rinsing tank 48 by guide sheave 74. From guide sheave 74 wire 78' passes to final idler sheave 76 and from thence continues to a draw bench where the wire is drawn through dies for reducing its diameter and finishing. From the draw bench the wire passes to a suitable collection point such as a reel. The collecting reel may be power driven so as to provide the necessary force to pull wire 78 through the plating and rinsing tanks.

A certain amount of liquid loss will take place during the plating process. Similarly, the iron content of the solution Will gradually build, as previously explained. For these reasons, handle 26 on the bin 20, valve 18 on the sulfuric acid feed, and water valve 19 are adjusted so as to maintain a continuous influx of raw materials in the proper proportions to mixing tank 10. These raw materials are added to the tank in suitable proportions to provide a continuous charge of new copper sulfate solution. At the same time, when the liquid level has reached the top of overflow pipe 50, a continuous fiow of recycled fluid is passed into the mixing tank from recycling conduit 52. The net result is that solution loss is continually compensated, while the tendency for iron buildup is simultaneously combatted. When the iron in the solution eventually builds to an undesirable level, the tank 10 may once again be drained to approximately half its volume and the cycle begun again,

The many advantages of this invention will be apparent. A continuous coating operation is hereby provided which is highly advantageous as compared to the batch method previously employed. Furthermore, not only is the method continuous, but the coating achieved on the Wire is much more uniform and of much higher quality than that previously obtained. Furthermore, the human labor required is materially reduced and costs are consequently lowered.

It will be readily understood that many variations and modifications of this invention are possible without departing from the spirit and scope thereof. For this reason the foregoing description is to be construed as illustrative only, rather than limiting. This invention is limited only by the scope of the following claim.

What I claim as new and desire to secure by Letters Patent of the United States is:

The method of continuously coating ferrous wire which comprises: preparing an initial volume of an aqueous copper sulfate solution; passing said solution at a controlled rate into a plating tank; recycling said solution from said plating tank to said initial volume; substantially continuously passing a strand of wire horizontally through said solution and periodically reversing the direction of travel of said wire through said solution to deposit thereon a substantially uniform copper coating; substantially continuously removing the so-plated portions of said strand from said solution; substantially continuously adding copper, sulfuric acid, and water to said initial volume in an amount sufficient to at least equal solution loss; and maintaining said initial volume in a state of substantially continuous agitation.

References Cited by the Examiner UNITED STATES PATENTS 1,771,379 7/1930 Johnson 117-128 X 1,891,501 12/1932 Candy 117-231 X 1,947,993 2/1934 Larsen 117-102 X 1,961,148 6/1934 Herman 118-420 X 2,394,066 2/1946 Kauth 117-128 2,445,372 7/1948 Trenbath 118-420 X 2,639,966 5/1953 Stanton 117-102 X 2,851,043 9/1958 Slovin 118-420 X 2,872,353 2/1959 Metheny 117-130 2,943,598 7/1960 Newton 118-420 X 3,020,224 2/1962 Blank et al 117-102 X 3,056,693 10/1962 Woock 117-102 JOSEPH B. SPENCER, Primary Examiner.

WILLIAM D. MARTIN, RICHARD D. NEVIUS,

Examiners. 

